Alright, I understand.
However, I wouldn’t try to copy Chads pistol squats if I were you. He’s more flexible than your, maybe genetically so as well, so trying full depth pistol squats when you’re not used to them can be horrible for both your knees and back.
Instead, maybe try doing them with your back straight and the resting leg beneath or behind you. In a pistol squat you bend your spine every repetition and put a lot of stress on your body if you’re not flexible enough in your ankles and hips.